bukkit NMS Accessing the Current Minecraft Version

Example

One of the most critical parts of dealing with NMS code is being able to support mulitple Minecraft versions. There are numerous ways to do this, but a simple solution is to use this code to store the version as a public static field:

public static final String NMS_VERSION = Bukkit.getServer().getClass().getPackage().getName().substring(23);

This code snippet works by taking the CraftServer class:

org.bukkit.craftbukkit.VERSION.CraftServer.class

Getting its package:

org.bukkit.craftbukkit.VERSION

And taking the substring of the package name starting at the index 23 which will always be after 'org.bukkit.craftbukkit.' (which has a length of 23 characters). Resulting in the final VERSION string:

VERSION

There are a number of reasons why it is so important to be able to access the current Minecraft version. Mostly because any accessing of a class on a server running a different Minecraft version than what the plugin was coding with will throw an Error.

Here is an example that demonstrates how to solve that issue by using the NMS_VERSION field to retrieve an instance of CraftPlayer (which is a NMS class) on any Minecraft version.

/**
 * Invokes the getHandle() method on the player's CraftPlayer instance to
 * retrieve the EntityPlayer representation of the player as an Object to
 * avoid package version change issues
 * 
 * @param player
 *            the player to cast
 * @return the NMS EnityPlayer representation of the player
 */
public static Object getCraftPlayer(Player player) {
    try {
        return Class.forName("org.bukkit.craftbukkit." + NMS_VERSION + ".entity.CraftPlayer")
                .getMethod("getHandle")
                .invoke(player);
    } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException | NoSuchMethodException | SecurityException | ClassNotFoundException e) {
        throw new Error(e);
    }
}

The resulting object can then be manipulated using reflection to perform NMS based tasks without worrying about trying to access the wrong version of the class.

Even this method is not foolproof however, as NMS field and method names change easily, so the only thing you're guaranteeing by doing this is that your code wont definitely break each time Minecraft updates.